From 5148726f2c272055ffa8e528a9280733679e4a06 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sat, 1 Dec 2018 01:36:59 +0800 Subject: [PATCH] sctp: kfree_rcu asoc [ Upstream commit fb6df5a6234c38a9c551559506a49a677ac6f07a ] In sctp_hash_transport/sctp_epaddr_lookup_transport, it dereferences a transport's asoc under rcu_read_lock while asoc is freed not after a grace period, which leads to a use-after-free panic. This patch fixes it by calling kfree_rcu to make asoc be freed after a grace period. Note that only the asoc's memory is delayed to free in the patch, it won't cause sk to linger longer. Thanks Neil and Marcelo to make this clear. Fixes: 7fda702f9315 ("sctp: use new rhlist interface on sctp transport rhashtable") Fixes: cd2b70875058 ("sctp: check duplicate node before inserting a new transport") Reported-by: syzbot+0b05d8aa7cb185107483@syzkaller.appspotmail.com Reported-by: syzbot+aad231d51b1923158444@syzkaller.appspotmail.com Suggested-by: Neil Horman Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/sctp/structs.h | 2 ++ net/sctp/associola.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index a11f937..feada35 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -2075,6 +2075,8 @@ struct sctp_association { __u64 abandoned_unsent[SCTP_PR_INDEX(MAX) + 1]; __u64 abandoned_sent[SCTP_PR_INDEX(MAX) + 1]; + + struct rcu_head rcu; }; diff --git a/net/sctp/associola.c b/net/sctp/associola.c index 6a28b96..3702f48 100644 --- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -434,7 +434,7 @@ static void sctp_association_destroy(struct sctp_association *asoc) WARN_ON(atomic_read(&asoc->rmem_alloc)); - kfree(asoc); + kfree_rcu(asoc, rcu); SCTP_DBG_OBJCNT_DEC(assoc); } -- 2.7.4